
Well, this manga gets it right in the sense that when you keep yearning for someone you haven't seen in a decade, then rather than love, it's more like mere fond memories. Same for Adachi's memories. And when that happens, once you are reunited the person you yearned for either manages to live up to your memories (making you "stay" inlove) or they don't (making you "fall out of love" with them).
Shinagawa didn't live up to the idealized memories Itabashi had kept of him, while Itabashi did live up to Adachi's, because he had stayed just as Adachi loved him: as a nice, unprejudiced dude who would never down on him (neither before, when he was poor, nor now that he was a yakuza).

Yes, you are right, but when did Itabashi start liking Adachi as a man? My point remains. It lacked transitioning. He fell out of love with Shinagawa, but then when he started acting shy around Adachi it felt shallow to me. Like, you like me, so I like you too now, which is fine, it happens. You get conscious of someone when they confess to you and you care for them, but I would have liked more moments building up to Itabashi falling for Adachi, since a couple scene's back he was yearning for Shinagawa (I'm referring to when he was measuring Adachi and got all shy with his flirting).
Anywas, it was a good story, but precisely bc of that, I wish it was even better lol. Can't fit everything into a few pages.
But when did Itabashi stop liking Shinagawa and fall for Adachi? I felt it lacked a bit of transition from one to the other.